Re: Acetone + ccHCl yields chlorine?

In article <1191913517.411448.32860@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, WS <novalidaddress@xxxxxxxxxxxxxx> wrote:
On Oct 9, 1:03 am, bruce.sincl...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
(Bruce Sinclair) wrote:
In article <1191880910.315037.94...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, WS
<novalidaddr...@xxxxxxxxxxxxxx> wrote:

Dear Experts,

I have prepared acidic acetone by mixing 95% (v) acetone and 5% (v)
conc. HCl in order to precipitate proteins from serum. After a few
minutes. the solution turned yellowish green (typical chlorine color),
what I didn't expect. There seems to be a weak smell of chlorine as
well. When I add up to 500ul (I haven't tried more) to 50ul serum,
Hi Bruce,

actually, I had planned to use 10% (m/v) trichloroacetic acid (TCA) in
acetone according to a procedure described by Chen et al. (http://
www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=158
80626)
to fractionate serum. As I didn't have TCA on the shelf, I tried the
mentioned mixture as the author compared it to and had found it worked
similar.

Thanks for that. I will look at the reference with interest.
We use TCA routinely (as well as a few precipitants) but AFAIK, we have
never combined them. If you go this way in the future, note that TCA is not
all that stable at 10 % w/w. Even at 30 % and stored in the fridge you'll
need to make up fresh every 2 weeks or so.

To the OP re TCA and acid ... I've found that TCA tends to break down to
chloroform over time (using the smell test :) ) ... and particularly quickly
if there is any OH around.

.

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